Endocrinology of Pregnancy Flashcards
Where is tubular fluid reabsorbed and what controls this process?
Rete testis
Early epididymis
This is under the control of oestrogen
Where do you find oestrogen within the male reproductive tract?
Tubular fluid produced by sertoli cells
What stimulates the release of nutrients and other molecules (e.g. glycoproteins) into the epididymal fluid?
Androgens
What are the roles of these secreted nutrients and molecules?
Provide energy for the impending journey
Coat the surface of the spermatozoon (to protect them from the hostile environment)
Within which part of the male reproductive tract is fluid reabsorbed and secretory products put in?
Epididymis
Why is the concentration of sperm in the vas deferens higher than further down the reproductive tract?
Further down the reproductive tract, other fluids and secretory products are added thus diluting the sperm.
Why is there fibrinogen and fibrinolytic enzymes in the seminal fluid?
After ejaculation, the semen initially clots and then must be broken down
Describe the capabilities of the spermatozoa in the vas deferens.
Capable of limited movement
Limited capability to fertilise an ovum
Which steroid precursor tends to be provided by the mother for the foetus?
Pregnenolone
Which androgen is formed by the maternal and foetal adrenals?This is used as a precursor for oestrogen production.
Dehydroepiandrosterone Sulphate (DHEAS)
Which oestrogens are produced by the placenta using DHEAS from the mother and foetus?
Oestradiol
Oestrone
What is the main oestrogen of pregnancy? Describe how it is produced.
OESTRIOL
DHEAS from the foetal adrenals is conjugated in the foetal liver to form 16-alpha-hydroxy DHEAS
16-alpha-hydroxy DHEAS is then de-conjugated in the placenta and used to produce oestriol
What can be measured to gage the health of the foetus?
Oestriol: oestradiol + oestrone levels
Oestriol: total oestrogens
What biochemical change is required for contraction of the uterus during parturition?
Increase in intracellular calcium concentration
Describe how oestrogen increases the chance of contraction.
Oestrogen binds to oestrogen receptors and triggers the synthesis of prostaglandins within the endometrial cells.
Prostaglandins stimulate the release of calcium from intracellular stores.
So oestrogen tends to increase the chance of contraction
Describe how oxytocin increases the chance of contraction.
Oxytocin binds to its receptor on the endometrial cell and opens calcium channels, allowing calcium ions to move in from outside
Describe the effect of progesterone on this contraction process.
Progesterone keeps the effects of oestrogen under control
Progesterone inhibits oestrogen receptors
Progesterone inhibits the production of prostaglandins
What change occurs when the foetus reaches a particular size, which is crucial for contraction to take place?
There is a switch in steroid synthesis from progesterone synthesis to oestrogen synthesis
This leads to oestrogen dominance –> prostaglandin production –> calcium release from intracellular stores –> promotion of muscle contraction
What 2 hormones are involved in milk production and milk ejection?
Prolactin – milk production
Oxytocin – milk ejection
These both have a similar neuroendocrine reflex arc stimulated by suckling
Contents of semen
Sperm
Seminal fluid
Leukocytes
Where does most seminal fluid come from
Seminal vesicles
Prostate
Bulbourethral
Role of capacitation
Achieve fertilising capacity of spermicide in female repro tract
3 parts to capacitation
Loss of glycoprotein coat
Change in surface membrane characteristic
Whiplash movements of tail
What is capacitation dependent of
Ca and oestrogen
Upon what does acrosome reaction occur
Binding to ZP3 glycoprotein of follicle
What does binding to ZP3 receptor stimulate
Ca influx
What is Ca2+ influx dependent of in acrosome reaction
Progesterone
What is effect of Ca influx in acrosome reaction
Release of hyaluronidase and proteolytic enzymes
Allows penetration of zone pellucida
Where does fertilisation occur
Fallopian tube
What does fertilisation trigger
Cortical reaction
Purpose of cortical reaction
Prevents further entry of sperm as degrades the zone pelluicda mainly the ZP3 and ZP2 receptors
Immediate development of conceptus
Can last up to 10 days but normally 3-4
Continues to divide all the way down to uterus
How does developing conceptus receive nutrients
Uterine secretions
Stages to implantation
Attachment
Decidualisation
What happens in attachment stage
Outer trophoblast cells contact uterine surface epithelium
What happens in decidualisation stage
Changes in underlying uterine stromal tissue
What’s needed for decidualisation stage
Progesterone dominating oestrogen
Important molecules in attachment of blastocyst
Leukaemia inhibitory factor
Interleukin 11
What secretes LIF
Endometrial secretory glands and maybe blastocyst
Role of LIF
Adhesion
What secretes IL11
Endometrial cells for adhesion
Main factor involved in decidualisation
IL11
Changesseen in endometrium during decidualisation
Glandular epithelial secretion
Glycogen accumulation in stromal cytoplasm
Growth of capillaries
Increased vascular permeability
Production of oestrogen and progesterone in first 40 days of pregnancy
Corpus luteum
What stimulates production of oestrogen and progesterone in first 40 days of pregnancy
hCG from trophoblasts acting on LH receptors
Role of oestrogen and progesterone in pregnancy
Essential for developing fetoplacental unit
Inhibits maternal LH and FSH
